Preheat oven to 450℉. Line 15 x 10 x 1-inch baking sheet with aluminum foil; spray lightly with cooking spray. Place 1/2 cup oats in food processor or blender. Process until finely ground; remove from food processor. Place cauliflower, onion and celery in large bowl. In small bowl, whisk together turmeric, thyme and salt, if desired. Stir in oil. Add to vegetables. Toss until well coated with turmeric mixture. Place vegetables on baking sheet. Add freshly ground pepper, as desired. Roast 15 minutes; stir and continue roasting 10 to 15 minutes or until vegetables are tender. Cool vegetables slightly. Place in food processor or blender. Add ginger and 1/2 cup broth. Process until pureed, adding additional broth if necessary. Transfer pureed vegetables to large saucepan or Dutch oven. Add remaining broth. Stir in ground oats. Bring to boil; reduce heat and simmer 15 minutes, stirring occasionally. Stir in remaining oats. Continue cooking 3 to 5 minutes or until oats are softened, stirring frequently. Add water or additional broth, if desired for consistency.